I’ve read some of Newton’s letters while doing research at the Royal Society archives. He definitely comes off as severely deficient in social skills just from the random sampling I looked at - I think one was complaining about his land lady offering him food. Granted, it’s impossible to know many things “for sure” in history but “Newton had a difficult personality” is a pretty good bet, based on those letters and the bios I’ve read.

Another fun fact from the letters - Newton invited the con artist George Psalmanazar over for lunch at some point circa 1703. Psalmanazar claimed to be a Taiwanese prince but had long blonde hair and a faint French accent. Unclear if Newton was taken in, but Halley was able to stump him with an astronomy-based question. Sounds like something from the Baroque Cycle but it all really happened.